1. Field of the Invention
The invention relates to a vehicle lamp used as a tail lamp or the like in which a signal is produced. More particularly, the invention relates to vehicle lamps which use several light sources, for example LED lamps or the like, each of which require a small amount of electric power.
2. Discussion of the Related Art
FIG. 5 illustrates a conventional automobile lamp 90 with a light source including several LED lamps 91. The LED lamps 91 are mounted on a printed wiring board 92 and are enclosed in a housing 93. The light emitting direction of the LED lamps 91 corresponds to the illuminating direction of the automobile lamp 90. The LED lamps 91 are covered by an outer lens 94 which has lens cut 94a on the inner surface of the outer lens 94.
The light rays produced by the LED lamps 91 are beam-formed luminous fluxes. The area of the outer lens 94 which is illuminated by a single LED lamp 91 is comparatively small. Accordingly, a plurality of LED lamps 91 are required to realize a uniformly lit surface for the outer lens 94.
In some instances the outer lens 94 is curved to fit the design of an automobile body and the distance between the LED lamps 91 and outer lens 94 differs with respect to each other. The difference in distance between the LED lamps 91 and outer lens 94 is due to the mounting configuration of the lamps 91 on the surface of a printed wiring board 92. Accordingly the size of the areas and the distance between the areas of the outer lens 94 illuminated by the LED lamps 91 is different with respect to each other. The printed wiring boards 92 can be attached in the automobile lamp 90 such that they form a broken line form or can be stacked in a stair configuration for mounting the LED lamps 91 at a uniform distance with respect to the outer lens 94.
The large number of LED lamps 91 required for the conventional automobile lamp 90 creates high manufacturing costs. Since the light illuminated by a LED lamp 91 is in a beam formation, the illuminated area of the outer lens 94 is narrow. Accordingly, in order to uniformly illuminate the outer lens 94, a plurality of LED lamps 91 are required. The large number of LED lamps 91 increases both the manufacturing and final product costs.
When the surface of the outer lens 94 has curved lines, the disposition of the printed wiring board 92 is difficult to determine. Accordingly, the position of the printed wiring board 92 with respect to the inner side of the outer lens 94 is not uniform, and the light distribution patterns of the lamps 90 may be different with respect to each other. Furthermore, the quality of the automobile lamp 90 may decrease and may not meet the requirements for each of the light distribution patterns due to the wiring board configuration.